Question

I want to replace some substrings in a string with wiki markup. E.g. I have a string

some other string before
; Methods
{{columns-list|3|
* [[Anomaly detection|Anomaly/outlier/change detection]]
* [[Association rule learning]]
* [[Statistical classification|Classification]]
* [[Cluster analysis]]
* [[Decision trees]]
* [[Factor analysis]]
* [[Neural Networks]]
* [[Regression analysis]]
* [[Structured data analysis (statistics)|Structured data analysis]]
* [[Sequence mining]]
* [[Text mining]]
}}

; Application domains
{{columns-list|3|
* [[Analytics]]
* [[Bioinformatics]]
* [[Business intelligence]]
* [[Data analysis]]
* [[Data warehouse]]
* [[Decision support system]]
* [[Drug Discovery]]
* [[Exploratory data analysis]]
* [[Predictive analytics]]
* [[Web mining]]
}}
some other string after

I want to replace the original substring by

[[Anomaly detection|Anomaly/outlier/change detection]]
[[Association rule learning]]
[[Statistical classification|Classification]]
[[Cluster analysis]]
[[Decision trees]]
[[Factor analysis]]
[[Neural Networks]]
[[Regression analysis]]
[[Structured data analysis (statistics)|Structured data analysis]]
[[Sequence mining]]
[[Text mining]]
[[Analytics]]
[[Bioinformatics]]
[[Business intelligence]]
[[Data analysis]]
[[Data warehouse]]
[[Decision support system]]
[[Drug Discovery]]
[[Exploratory data analysis]]
[[Predictive analytics]]
[[Web mining]]

I’ve tried some regex expressions to extract stuff in {{ }} first. But I always got None.

ADD: The problem is that I’m only interested in the contents in [[]] which itself is in {{}}. I have some other occurrences of [[]] in other part of the string.

So, how could I do this by using re.sub? Thanks

ADD: current solution (ugly)

def regt(matchobj):
  #store matchobj.group(0) somewhere else, later on add them to the string
  #Next, another function will remove all {{}} alway
  return ''

matches = re.sub(r'\[\[.*?\]\](?=[^{]*\}\})', regt,wiki_string2)

Answer 1

Match it instead of replacing it

\[\[.*?\]\](?=[^{]*\}\})

---

.*? matches lazily.so it would stop at the first time ]] occurs

.* matches greedily.so it would stop at the last time ]] occurs

---

(?=[^{]*}}) is a lookahead which means match content within [[ ]] only if it is followed by 0 to many characters except { till }}..

This is done because you want to match [[``]] if it is within {{ }}..

So characters after ]] would be any character except { till }}..

So this would avoid cases like this

[[xyz]]<-this would not match since { after it
{{
[[xyz]]<-this would match since it is not followed by { and it reaches }}
[[xyz]]<-this would match since it is not followed by { and it reaches }}
}}